ROE is what most talk about.I have never had $250k cash to invest in the market not that rich or high income but have accumulated with effort much more equity and then cash flow from years of ownership.

You can accumulate some cash just be patient and stop spending and buying.

For example, if the market rent on the duplex unit you'd like to occupy is $500/mo, you can go rent another similar unit for $500 (-$500/mo on your personal bank account) and rent out the units owned by your Solo 401k (+$500/mo for your Solo 401k).As you can see, -$500 and +$500 equal the same net effect in the short term, but long term, you'll accumulate wealth more rapidly because when you go to reinvest the cashflow from the 401k-owned unit you were going to occupy (but rented out instead), the tax benefits of full reinvestment will add up faster.How do I pay the returns back to the 401(k)?

However, we have a long-term plan to accumulate more than 10 properties and want to be strategic in the way we structure which one of us is on each of our loans now so that we can max out at 20 Fannie/Freddie loans in our individual names. 

You would transfer all the depreciable assets from the individual return to the partnership return.Make sure to property include basis, accumulated depreciation, date placed into service, etc.Best of luck.

I have some investment experience and have accumulated some idle funds.

I'm absolutely thrilled to be investing in real estate but I'm not willing to risk what took 25 years to build.Here is my approach:Consider a worst-case scenario - I accumulate a portfolio of rental properties.

As I am set up now, all rent proceeds go into my checkbook LLC account and rot there until I accumulate some and put it to use elsewhere.

May be you could think this in later time, when you accumulated enough wealth.  

Second Set Clear Goals Are you looking for long-term wealth accumulation, steady income, or both?